featureworks is not able to work with assemblies because is detecting only the part's features.
to avoid the 100 files opening you could try to create a macro that runs 3 operations for all the files of your assembly :
1.open/edit the file
3.close and save the part file.
I've also thought about this option but I came across another problem at first:
For example: If I've got an assembly of only 3 parts it would be not much work to open each and save it with the recognized features.
The problem is that I have to save the parts with another filename. And even if I rename it to the name it had before, how is it possible not to loose the assembly positions of each part?
All I have to do is removing a lot of features to get a simplified assembly. But I want to keep the assembly. Do you have any other ideas of how to realize that?
it's enough to go to FeatureWorks Options and flag to override the current file